The right of priority under 35 U.S.C. xc2xa7119(a) is claimed based on German Patent Application No. 101 05 202.2, filed Jan. 31, 2001, the entire disclosure of which is hereby incorporated by reference.
The present invention relates to a heat-exchanger tube block comprising at least two header tubes, each having a C-shaped cross section and having a continuous longitudinal slot, and flat tubes inserted into the header-tube longitudinal slots. Tube blocks of this type are employed, for example, in heat exchangers for motor vehicle air-conditioning installations.
DE 198 462 67 A1 describes such a heat-exchanger tube block, which includes a stack of straight flat tubes whose ends are inserted into one longitudinal slot on each of two header tubes. The header tubes are arranged in parallel along two mutually opposite block sides. The header tubes can be manufactured from respective tube blanks, in which the continuous longitudinal slot is inserted by milling or the like or is manufactured by bending a respective sheet-metal strip around into the desired C cross-sectional shape. A cup-shaped sleeve is fitted over the appropriate end of the header tube, as an end cover. On the one hand, the bottom of this cup-shaped sleeve axially covers the header tube and on the other hand, by means of a corresponding side wall region, it radially covers a part of the longitudinal slot which is possibly still free and is not completely filled by the inserted flat-tube ends.
In certain applications, a plurality of header tubes are arranged close to one another. As an example, DE 197 29 497 A1 discloses an evaporator tube block having serpentine-shaped flat tubes whose ends are fitted into a common connecting tube. The connecting tube includes two parallel, abutting header tubes as integrated constituent parts. In the usual manner, one of these header tubes functions as the actual collector-tube (outlet) duct and the other as the distributor-tube (inlet) duct.
One principal object of the present invention is to provide a novel heat-exchanger tube block that can be manufactured with relatively little expense and/or complexity and yet possesses the necessary fluid-tightness and pressure resistance, so that it can be used, e.g., in a CO2-based automotive air-conditioning system.
A further object of the invention is to provide an automotive air-conditioning system embodying the improved heat exchanger tube block according to the invention.
In accordance with one aspect of the present invention, there has been provided a heat-exchanger tube block, comprising: at least two header tubes, each of which has a C-shaped cross section defining an inner flow cross-section and a continuous longitudinal slot therein; at least two flat tubes inserted into the header-tube longitudinal slots; and a first cover-plate element having a plurality of C-shaped openings therein, the first cover-plate element being applied to a first end of the at least two header tubes, such that each header tube respectively fits into one of the openings and is secured therein in a fluid-tight manner.
In a preferred embodiment, the tube block further comprises a second cover-plate element applied to a second end of the at least two header tubes. The second cover-plate element has a plurality of openings for fitting over each respective header tube, such that the openings leave the inner header-tube flow cross section at least partially open.
In accordance with another aspect of the invention, there has been provided an automotive air-conditioning system comprising a heat exchanger having a tube block, wherein the tube block comprises the improved tube block described above.
Further objects, features and advantages of the present invention will become apparent from the detailed description of preferred embodiments that follows, when considered together with the accompanying figures of drawing.